diff --git a/lib/libsys/procctl.2 b/lib/libsys/procctl.2
--- a/lib/libsys/procctl.2
+++ b/lib/libsys/procctl.2
@@ -755,6 +755,10 @@
 .Fa idtype
 and
 .Fa id .
+.It Bq Er ESRCH
+When handling a
+.Dv PROC_REAP_KILL
+request the reaper process has no children processes to kill.
 .It Bq Er EINVAL
 An invalid operation or flag was passed in
 .Fa data